iOS7 MKMapView 截图 [英] Snapshot of MKMapView in iOS7

问题描述

我正在尝试在 iOS7 应用程序中创建 MKMapView 的快照，就像在以前的 iOS 版本中到处推荐的那样:

I am trying to create a snapshot of a MKMapView in iOS7 application the same way it's recommended everywhere for previous iOS versions:

- (UIImage*) renderMapViewToImage
{
   UIGraphicsBeginImageContextWithOptions(mapView.frame.size, NO, 0.0);
   [mapView.layer renderInContext:UIGraphicsGetCurrentContext()];
   UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
   UIGraphicsEndImageContext(); 
   return image;
}

然而，返回的图像是一个黑色矩形，上面有一个蓝色的当前位置点.我也尝试过使用 mapView 的不同子层，但结果总是一样的.

However, the image returned is a black rectangle with a blue current location dot on top of it. I've tried using different sublayers of the mapView as well, but the result is always the same.

有人知道如何在 iOS7 中拍摄 MKMapView 快照吗?

Does anyone know how to take MKMapView snapshots in iOS7 ?

推荐答案

您可以使用 MKMapSnapshotter 并从生成的 MKMapSnapshot 中获取 image.请参阅 WWDC 2013 会议视频对其的讨论，透视 Map Kit.

You can use MKMapSnapshotter and grab the image from the resulting MKMapSnapshot. See the discussion of it WWDC 2013 session video, Putting Map Kit in Perspective.

例如:

MKMapSnapshotOptions *options = [[MKMapSnapshotOptions alloc] init];
options.region = self.mapView.region;
options.scale = [UIScreen mainScreen].scale;
options.size = self.mapView.frame.size;

MKMapSnapshotter *snapshotter = [[MKMapSnapshotter alloc] initWithOptions:options];
[snapshotter startWithCompletionHandler:^(MKMapSnapshot *snapshot, NSError *error) {
    UIImage *image = snapshot.image;
    NSData *data = UIImagePNGRepresentation(image);
    [data writeToFile:[self snapshotFilename] atomically:YES];
}];

话虽如此，renderInContext 解决方案仍然适用于我.有关于只在 iOS7 的主队列中这样做的说明，但它似乎仍然有效.但是 MKMapSnapshotter 似乎是更适合 iOS7 的解决方案.

Having said that, the renderInContext solution still works for me. There are notes about only doing that in the main queue in iOS7, but it still seems to work. But MKMapSnapshotter seems like the more appropriate solution for iOS7.

如果你想在快照中包含一些注释，你必须手动绘制它们(！).在透视地图工具包视频的末尾详细讨论了这一点.我不得不说，这是我见过的 Apple 建议的最不优雅的实现之一.无论如何，在 iOS 中，它可能看起来像:

If you want to include some annotations in the snapshot, you have to draw them manually (!). This is discussed in some detail at the end of the Putting Map Kit in Perspective video. I have to say that this is one of the least elegant implementations that I've ever seen Apple advise. Anyway, in iOS, it might look like:

MKMapSnapshotOptions *options = [[MKMapSnapshotOptions alloc] init];
options.region = self.mapView.region;
options.scale = [UIScreen mainScreen].scale;
options.size = self.mapView.frame.size;

MKMapSnapshotter *snapshotter = [[MKMapSnapshotter alloc] initWithOptions:options];
[snapshotter startWithQueue:dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0) completionHandler:^(MKMapSnapshot *snapshot, NSError *error) {

    // get the image associated with the snapshot

    UIImage *image = snapshot.image;

    // Get the size of the final image

    CGRect finalImageRect = CGRectMake(0, 0, image.size.width, image.size.height);

    // Get a standard annotation view pin. Clearly, Apple assumes that we'll only want to draw standard annotation pins!

    MKAnnotationView *pin = [[MKPinAnnotationView alloc] initWithAnnotation:nil reuseIdentifier:@""];
    UIImage *pinImage = pin.image;

    // ok, let's start to create our final image

    UIGraphicsBeginImageContextWithOptions(image.size, YES, image.scale);

    // first, draw the image from the snapshotter

    [image drawAtPoint:CGPointMake(0, 0)];

    // now, let's iterate through the annotations and draw them, too

    for (id<MKAnnotation>annotation in self.mapView.annotations)
    {
        CGPoint point = [snapshot pointForCoordinate:annotation.coordinate];
        if (CGRectContainsPoint(finalImageRect, point)) // this is too conservative, but you get the idea
        {
            CGPoint pinCenterOffset = pin.centerOffset;
            point.x -= pin.bounds.size.width / 2.0;
            point.y -= pin.bounds.size.height / 2.0;
            point.x += pinCenterOffset.x;
            point.y += pinCenterOffset.y;

            [pinImage drawAtPoint:point];
        }
    }

    // grab the final image

    UIImage *finalImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    // and save it

    NSData *data = UIImagePNGRepresentation(finalImage);
    [data writeToFile:[self snapshotFilename] atomically:YES];
}];

对于 MacOS 实现，请参阅该视频了解更多信息，但技术基本相同(创建图像的机制略有不同).

For MacOS implementation, see that video for more information, but the technique is basically the same (the mechanism for creating the images is slightly different).

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